1. Field of the Invention
This invention relates to locks wherein a cylindrical barrel is prevented from turning, thereby permitting opening of the lock, by electromagnetically actuated armatures which engage the barrel to prevent its turning in the body of the lock. An electronic circuit associated with the lock provides for the energization of an electromagnet which withdraws the armatures from contact with the barrel thereby permitting its rotating to open the lock. A key received in a slot in the barrel of the lock is coded, for instance, magnetically or optically, such that if it bears a predetermined code, the electronic circuit will respond to the code to energize the electromagnet to permit rotation of the barrel to open of the lock.
2. Description of Related Art Including Information Disclosed under Secs. 1.97-1.99
In locks of the type set forth above, the armatures were located such that it has been possible to break a portion of the barrel, by inserting an instrument through the key slot, such that the barrel may be rotated to open the lock even though the electromagnet has not been energized to withdraw the armatures from engagement with the barrel. That is, by breaking away a portion of the barrel, it is possible to insert an instrument through the key slot into engagement with the armature to move the armature out of engagement with the barrel so as to permit rotation of the barrel.